1. Field of the Invention
The present invention generally relates to detecting biological and chemical material and, more particularly, to systems and methods of hybridizing nucleic acid in experiments in order to analyze a DNA sequence, and to detect biological materials such as proteins and ATPs.
2. Discussion of Background
As the end of human genome sequence research approaches, increasingly more attempts have been made to make full use of gene information in the medical arena. As post genome-sequence researches, gene expression analysis and analysis of single nucleotide polymorphisms (SNPs) in genes attract special attention. To elucidate the casual relationship between the functions of genes or genes themselves and diseases or drug sensitivity, the genes expressing under various conditions and gene mutation in the individuals are studied. Now, this accumulated knowledge of genes is used to diagnose diseases.
In diagnosing diseases, typing of the known genes or the presence of their mutation is involved unlike searching for unknown genes. It is preferable that it may be performed at a low cost and to do so, various types of methods have been developed. In the future, a wide range of tests from diagnosing diseases based on single genes to diagnosing diseases developing due to the synergy effect between various genes and the environmental conditions and testing plural genes for identifying drug sensitivity will attract special attention. In this case, it is desirable that many kinds of genes can be tested concurrently instead of individual genes or gene mutation. The system, which enables SNPs to be tested including the process for amplifying the target site of the gene at a low cost, is being sought. The systems applicable to SNP analysis or genetic testing include Invader assay (Science 260, 778 (1993)), Taqman assay (J. Clin. Microbio 1.34, 2933 (1996)), DNA microarray (Nature Gent. 18, 91 (1998), and pyrosequencing (Science 281, 363 (1998)). Among others, the DNA microarray, which allows many sites to be tested, attracts attention as a future gene sequencing technique.
In the microarray technique, various types of oligo DNAs or cDNAs are spotted on slide glass plates coated with poly-L-lysine. Spotting is performed using a device called spotter (or, arrayer), which can form spots with a diameter of several tens to 200 μm at an interval of 100 to 500 μm. The spotted oligo DNAs or cDNAs are post-processed, dried in the room, and stored. A target sample is prepared by extracting RNAs from a sample cell and preparing cDNAs marked with any of fluorescent dyes such as Cyanine3 and Cyanine5. The target sample solution is dropped on the microarray and incubated in a moisture chamber at 65° C. for about 10 hours. After hybridization ends, the microarray is washed with a 0.1% SDS solution and dried at room temperature. To evaluate the microarray, a scanner is used. An argon ion laser, for example, is used for an exiting light source and a photomultiplier tube, for example, is used for a luminescent detector. Any influence of a background irradiated from any other points than a focal point is eliminated using a confocal optics, improving an S/N ratio. To evaluate fluorescence at many spots, the microarray needs to be aligned with a reading optics at a high accuracy. For this,reason, the scanner has an x-y stage, which can move within an error of 10 μm or less.
The method for implementing low-cost measurement by integrating and miniaturizing the sensor and radio communication parts has been proposed (Bult, K., et al.,: Proceedings of International Symposium on Low Power Electronics and Design, IEEE (1996), p 17–22, or Asada, G., et al.,: Proceedings of the European Solid-State Circuit Conference ESSCIRC'98 p 9–16). The method for supplying the power required by the integrated sensor and signal processing circuit using RF (radio frequency) (Huang, Q., Oberle, M.,: IEEE Journal of Solid-State Circuits vol. 33 (1998) p 937–946 or Neukomm, P., Rencoroni, I. and Quick, H.,: 15th International Symposium in Biotelemetry (1999) p 609–617) or infrared ray (U.S. Pat. No. 5,981,166) has also been proposed. In these conventional examples, one sensor chip is generally installed for each target to be measured such as a single sample or in the apparatus intended to measure one test term. In addition, in these examples, the information on the result of-detection by the sensor is sent by the radio communication part but no description of information communication for identifying the target to be measured is found. In this device the sensor can not be installed for each of plural identified targets to be measured or in the apparatus for measuring plural terms to be tested.
The method for using microparticles to determine the presence and concentration of biological molecules has also been disclosed (U.S. Pat. No. 6,051,377). In this method, index numbers are assigned to individual particles. The presence and concentration of biological molecules are detected using fluorescence, luminescence, or radiation while index numbers are decoded independently.
To implement the measurement system for biological and chemical samples, which is widely applicable to genetic and protein testing in the medical arena, foods, environmental measurement systems, process control in the chemical plants, and the like, it is required that: (1) the measurement system is small-sized, (2) many items can be tested in a single reaction cell, (3) the, test requires a shorter time, (4) not only biological materials such as nucleic acid and proteins, but also temperature, pressure, pH, and ion concentration can be identified, and (5) a small amount of sample is sufficient for testing.
The microarray is the slide glass plate, on which probe DNAs with diameters of several tens to several hundreds μm have been spotted. To form the spots, the device called a spotter drops a solution containing various probes on the slide glass plate. To ensure that a small amount of sample can be reacted with many probes, the spots must be formed at a high density, and the spots mentioned above are arranged at an interval of several tens to several hundreds μm. For this reason, it is desirable that the spotter has performance, which can form the spots at a high accuracy of position with an error of 10 μm or less. Since spotted amounts and shapes of solution may lead to any variation in measured value for fluorescent intensity during evaluation, the spotter must has performance, which can form the spots at a high uniformity. It has been eagerly sought that the measurement device, which allows the probes to be fixed uniformly and the desired various probes to be easily selected for measurement, avoiding this problem, is developed.
With respect to the device for detecting signals, fluorescent detection is used for the microarray as mentioned above. In this case, a laser as an exciting light source, a confocal optics, a photomultiplier tube, and a high accuracy x and y movable stage are required. Accordingly, it is difficult that the microarray is miniaturized and manufactured at a low cost and an economical and easy detection device has been sought. The microarray is a useful technique in that many items can be tested concurrently while generally, the reaction rate of target DNA hybridization with the probes fixed on the substrate is slow requiring about ten hours in some cases and it is difficult to improve its throughput. For this reason, it has been sought that an easy and speedy testing method is developed.
To not only measure biological materials such as nucleic acid and proteins but also measure physically and chemically temperature, pressure, and ion concentration, a lead line is required to output sensor signals. Measurement of many items, in particular, requires excess space and cost in lead line wiring, line connection, and signal processing. The advent of the measurement system, in which no lead line is required because the detection and measurement parts are not in contact with one another, and which enables many items to be easily tested has been expected. Such a technique is also necessary that the measurement apparatus with a sensor for sensing biological or chemical materials mentioned above and the sensor for measuring physical and chemical amounts are put together in the same reaction cell for concurrent measurement.
Moreover, in prior art disclosed in U.S. Pat. No. 6,051,377, the detection of captured biological molecules on the microparticles takes time because individual particles are detected and requires the mechanisms for detecting biological molecules and index numbers. To overcome this problem, the measurement system, in which the same mechanism can detect the captured biological molecules on the microparticles and index numbers, has been desired.